Jean Swesey was doing homework with her son in Cottonwood when it happened.
"It was a whole series of booms," Swesey said. "Up to six or seven. It was fast, it went loud. We were quiet and then my daughter down the hall screams really loud, ‘Did you hear that?' I sat there for a second and I heard another set."
Swesey wasn't alone. Residents in communities in and around Verde Valley and as far as Flagstaff called 911 or their police and fire departments to report the strange booming sounds.
"It sounded like thunder, but underground," Swesey said. "Like muffled thunder. And all the dogs in the neighborhood, all of them that were outside all started barking at once."
CBS 5 News first received reports of the explosion-like noises shortly after 5 p.m. Tuesday and began checking with law enforcement and government sources. The U.S. Geological Survey reports no significant earthquake activity in Arizona that could have created the booms.